Biological Invasions

, Volume 3, Issue 4, pp 323–332 | Cite as

Safe Site and Seed Limitation in Cytisus Scoparius (Scotch Broom): Invasibility, Disturbance, and the Role of Cryptogams in a Glacial Outwash Prairie

  • Ingrid M. Parker

Abstract

In all plant populations, establishment is controlled by two factors: the supply of propagules and their access to ‘safe sites’ for growth. An infestation of invading pest plants results in a seed-production gradient, from the edge where seeds are limiting, to the center where seeds may be in excess. Do invaded sites become ‘saturated’ with seeds? How rapidly does this occur, and how does the process depend on the availability of safe sites? Are safe sites, and consequently invasion, promoted by disturbance? I quantified the response of seedling establishment to seed input and disturbance in Cytisus scoparius (Scotch broom), an exotic shrub invading glacial outwash prairie remnants in western Washington, USA. I used disturbance treatments to investigate the role of the thick cryptogamic layer in these prairies, disturbing cryptogams by scraping or by fire. The effect of fire was partitioned into two factors: burning of the background vegetation/substrate versus breaking C. scoparius seed dormancy, by adding seeds either before or after the burn. Seed treatments ranged from 20 to 1000 seeds per m2. Both seed number and surface treatment showed significant effects on seedling density, along with a significant interaction between the two factors. Disturbance did not promote C. scoparius establishment; undisturbed plots produced more seedlings than burned or scraped plots. Within the burned plots, fire scarification appeared to increase germination but this effect was not significant. For germinated seedlings, mortality through the dry season (June–August) was not significantly different among surface treatments, nor did survivorship depend on density, with the result that initial differences in germination among the treatments persisted. The message that the undisturbed cryptogam layer facilitates C. scoparius establishment suggests that ‘ecosystem management’ strategies promoting healthy, undisturbed sites will not always be effective against invasive pest species.

disturbance exotic Fabaceae fire invasion resistance recruitment limitation Sarothamnus 

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References

  1. Andersen AN (1989) How important is seed predation to recruitment in stable populations of long-lived perennials? Oecologia (Berlin) 81: 310-315Google Scholar
  2. Anderson DC,Harper KT andHolmgren RC (1982) Factors influencing development of cryptogamic soil crusts in Utah deserts. Journal of Range Management 35: 180-185Google Scholar
  3. Belnap J (1993) Recovery rates of cryptobiotic crusts: Inoculant use assessment methods. Great Basin Naturalist 53: 89-95Google Scholar
  4. Bliss LC andGold WG (1999) Vascular plant reproduction, establishment, and growth and the effects of cryptogamic crusts within a polar desert ecosystem, Devon Island, N.W.T., Canada. Canadian Journal of Botany 77: 623-636Google Scholar
  5. Bossard CC (1990a) Secrets of an ecological interloper: Ecological studies on Cytisus scoparius in California. PhD Thesis. University of California, DavisGoogle Scholar
  6. Bossard CC (1990b) Tracing of ant-dispersed seeds: a newtechnique. Ecology (Tempe) 71: 2370-2371Google Scholar
  7. Bossard CC (1991) The role of habitat disturbance, seed predation and ant dispersal on establishment of the exotic shrub Cytisus scoparius in California. American Midland Naturalist 126: 1-13Google Scholar
  8. Bossard CC,Randall JM andHoshovsky MC (eds) (2000) Invasive Plants of California's Wildlands. University of California Press, BerkeleyGoogle Scholar
  9. Chappell CB andCrawford RC (1997) Native vegetation of the south Puget Sound prairie landscape. In: Dunn P andEwing K (eds) Ecology and Conservation of the South Puget Sound Prairie Landscape, pp 107-122. The Nature Conservancy, Seattle, WashingtonGoogle Scholar
  10. Crawley MJ (1990) The population dynamics of plants. Philosophical Transactions of the Royal Society of London B Biological Sciences 330: 125-140Google Scholar
  11. Crawley MJ (1992) Seed predators and population dynamics. In: Fenner M (ed) Seeds: The Ecology of Regeneration in Plant Communities, pp 157-191. CAB International, Wallingford, UKGoogle Scholar
  12. Cross JR (1981) The establishment of Rhododendron ponticum in the Killarny oakwoods, S.W. Ireland. Journal of Ecology 69: 807-824Google Scholar
  13. Downey PO (2000) Broom (Cytisus scoparius (L.) Link) and fire: Management implications. Plant Protection Quarterly 15: 178-183Google Scholar
  14. Downey PO andSmith JMB (2000) Demography of the invasive shrub Scotch broom (Cytisus scoparius) at Barrington Tops, New SouthWales: Insights for management. Austral Ecology 25: 477-485Google Scholar
  15. Dunn P andEwing K (eds) (1997) Ecology and Conservation of the South Puget Sound Prairie Landscape. The Nature Conservancy, Seattle, WashingtonGoogle Scholar
  16. Eldridge DJ (1993) Cryptogams, vascular plants, and soil hydrological relations: Some preliminary results from the semiarid woodlands of eastern Australia. Great Basin Naturalist 53: 48-58Google Scholar
  17. Eriksson O andEhrlen J (1992) Seed and Microsite Limitation of Recruitment in Plant Populations. Oecologia (Berlin) 91: 360-364Google Scholar
  18. Ewel JJ (1986) Invasibility: Lessons from south Florida. In: Mooney HA andDrake JA (eds) Ecology of Biological Invasions of North America and Hawaii, pp 214-249. Springer-Verlag, New YorkGoogle Scholar
  19. Franklin JF andDyrness CT (1988) Natural vegetation of Oregon and Washington. Oregon State University Press, CorvallisGoogle Scholar
  20. Gentle CB andDuggin JA (1997) Lantana camara L. invasions in dry rainforest-open forest ecotones: The role of disturbances associated with fire and cattle grazing. Australian Journal of Ecology 22: 298-306Google Scholar
  21. Gilkey HM (1957) Weeds of the Pacific Northwest. Oregon State College, CorvallisGoogle Scholar
  22. Gold WG (1998) The influence of cryptogamic crusts on the thermal environment and temperature relations of plants in a high arctic polar desert, Devon Island, N.W.T., Canada. Arctic and Alpine Research 30: 108-120Google Scholar
  23. Gold WG,Glew KA andDickson LG (2001) Functional influences of cryptobiotic surface crusts in an alpine tundra basin of the Olympic Mountains, Washington, USA. Northwest Science 75: 315-326Google Scholar
  24. Harper JL (1977) Population Biology of Plants. Academic Press, New YorkGoogle Scholar
  25. Harper KT andBelnap J (2001) The influence of biological soil crusts on mineral uptake by associated vascular plants. Journal of Arid Environments 47: 347-357Google Scholar
  26. Harper KT andMarble JR (1988) A role for nonvascular plants in management of arid and semiarid rangelands. In: Tueller PT (ed) Application of Plant Sciences to Rangeland Management and Inventory, pp 135-169. Kluwer Academic Publishers, BostonGoogle Scholar
  27. Harper KT andPendleton RL (1993) Cyanobacteria and cyanolichens: Can they enhance availability of essential minerals for higher plants? Great Basin Naturalist 53: 59-72Google Scholar
  28. Hartway C andSteinberg EK (1997) The influence of pocket gopher disturbance on the distribution and diversity of plants in western Washington prairies. In: Dunn P andEwing K (eds) Ecology and Conservation of the South Puget Sound Prairie Landscape, pp 131-139. The Nature Conservancy, Seattle, WashingtonGoogle Scholar
  29. Hobbs RJ (1989) The nature and effects of disturbance relative to invasions. In: Drake JA,Mooney HA,di Castri F et al. (eds) Biological Invasions: A Global Perspective, pp 389-405. Wiley & Sons, New YorkGoogle Scholar
  30. Hobbs RJ andHuenneke LF (1992) Disturbance, diversity, and invasion: Implications for conservation. Conservation Biology 6: 324-337Google Scholar
  31. Hobbs RJ andMooney HA (1985) Community and population dynamics of serpentine grassland annuals in relation to gopher disturbance. Oecologia (Berlin) 67: 342-351Google Scholar
  32. Hoffmann JH andMoran VC (1991) Biological Control of Sesbania-Punicea Fabaceae in South Africa. Agriculture Ecosystems and Environment 37: 157-174Google Scholar
  33. Hoshovsky M (1986) Element Stewardship Abstract for Cytisus scoparius and Cytisus monspessulanus, Scotch broom and French broom. The Nature Conservancy, Arlington, VirginiaGoogle Scholar
  34. Isaacson DL (2000) Impacts of broom (Cytisus scoparius) in western North America. Plant Protection Quarterly 15: 145-148Google Scholar
  35. Jesson L,Kelly D andSparrow A (2000) The importance of dispersal, disturbance, and competition for exotic plant invasions in Arthur's Pass National Park, NewZealand. NewZealand Journal of Botany 38: 451-468Google Scholar
  36. Johansen JR,St Clair LL,Webb BL andNebeker GT (1984) Recovery patterns of cryptogamic soil crusts in desert rangelands following fire disturbance. Bryologist 87: 238-243Google Scholar
  37. Johansen JR,Ashley J andRayburn WR (1993) Effects of range-fire on soil algal crusts in semiarid shrub-steppe of the Lower Columbia Basin and their subsequent recovery. Great Basin Naturalist 53: 73-88Google Scholar
  38. King SE andGrace JB (2000) The effects of gap size and disturbance type on invasion of wet pine savanna by cogongrass, Imperata cylindrica (Poaceae). American Journal of Botany 87: 1279-1286Google Scholar
  39. Kotanen PM (1995) Responses of vegetation to a changing regime of disturbance: Effects of feral pigs in a Californian coastal prairie. Ecography 18: 190-198Google Scholar
  40. Kruckeberg AR (1991) The Natural History of Puget Sound Country. University of Washington Press, Seattle, WashingtonGoogle Scholar
  41. Lewontin RC (1965) Selection for colonizing ability. In: Baker HG andStebbins GL (eds) The Genetics of Colonizing Species, pp 79-94. Academic Press, New YorkGoogle Scholar
  42. Louda SM (1982) Distribution ecology: Variation in plant recruitment over a gradient in relation to insect seed predation. Ecological Monographs 52: 25-41Google Scholar
  43. Louda SM andPotvin MA (1995) Effect of inflorescence-feeding insects on the demography and lifetime fitness of a native plant. Ecology (Washington DC) 76: 229-245Google Scholar
  44. Louda SM,Potvin MA andCollinge SK (1990) Predispersal seed predation, postdispersal seed predation and competition in the recruitment of seedlings of a native thistle in Sandhills prairie (Nebraska, USA). American Midland Naturalist 124: 105-113Google Scholar
  45. Maron JL andGardner SN (2000) Consumer pressure, seed versus safe-site limitation, and plant population dynamics. Oecologia (Berlin) 124: 260-269Google Scholar
  46. McClintock E (1985) Status reports on invasive weeds: Brooms. Fremontia 12: 17-18Google Scholar
  47. Metting B (1991) Biological surface features of semiarid lands and deserts. In: Skujins J (ed) Semiarid Lands and Deserts: Soil Resource and Reclamation, pp 257-293. Marcel Dekker, New YorkGoogle Scholar
  48. Mobley L (1954) Scotch broom, a menace to forest, range, and agricultural land. Proceedings of the 6th Annual California Weed Conference, pp 39-42Google Scholar
  49. Orians GH (1986) Site characteristics favoring invasions. In: Mooney HA andDrake JA (eds) Ecology of Biological Invasions of North America and Hawaii, pp 133-148. Springer-Verlag, New YorkGoogle Scholar
  50. Parendes LA andJones JA (2000) Role of light availability and dispersal in exotic plant invasion along roads and streams in the H.J. Andrews Experimental Forest, Oregon. Conservation Biology 14: 64-75Google Scholar
  51. Parker IM (1996) Ecological factors affecting rates of population growth and spread in Cytisus scoparius, an invasive exotic shrub. PhD Thesis. University of WashingtonGoogle Scholar
  52. Parker IM (2000) Invasion dynamics of Cytisus scoparius: A matrix model approach. Ecological Applications 10: 726-743Google Scholar
  53. Parker IM,Mertens SK andSchemske DW (1993) Distribution of seven native and two exotic plants in a tallgrass prairie in southeastern Wisconsin: The importance of human disturbance. The American Midland Naturalist 130: 43-55Google Scholar
  54. Paynter Q,Fowler SV,Memmott J,Shaw RH andSheppard AW (2000) Determinants of broom (Cytisus scoparius (L.) Link) abundance in Europe. Plant Protection Quarterly 15: 149-155Google Scholar
  55. Paynter Q,Fowler SV,Memmott J andSheppard AW (1998) Factors affecting the establishment of Cytisus scoparius in southern France: Implications for managing both native and exotic populations. Journal of Applied Ecology 35: 582-595Google Scholar
  56. Rees M andPaynter Q (1997) Biological control of Scotch broom: Modelling the determinants of abundance and the potential impact of introduced insect herbivores. Journal of Applied Ecology 34: 1203-1221Google Scholar
  57. Reifner RE andBowler PA (1995) Cushion-like fruticose lichens as Dudleya seed traps and nurseries in coastal communities. Madroño 42: 81-82Google Scholar
  58. Sheppard A,Hodge P andPaynter Q (2000) Factors affecting broom regeneration in Australia and their management implications. Plant Protection Quarterly 15: 156-161Google Scholar
  59. Snedecor GW andCochran WG (1989) Statistical Methods. Iowa State University Press, AimesGoogle Scholar
  60. St Clair LL,Webb BL,Johansen JR andBebeker GT (1984) Cryptogamic soil crusts: Enhancement of seedling establishment in disturbed and undisturbed areas. Reclamation and Revegetation Research 3: 129-136Google Scholar
  61. Tveten R (1997) Fire effects on prairie vegetation, Fort Lewis, Washington. In: Dunn P andEwing K (eds) Ecology and Conservation of the South Puget Sound Prairie Landscape, pp 123-130. The Nature Conservancy, Seattle, WashingtonGoogle Scholar
  62. Tveten RK andFonda RW (1999) Fire effects on prairies and oak woodlands on Fort Lewis, Washington. Northwest Science 73: 145-158Google Scholar
  63. US Army Corps of Engineers (1994) Final Environmental Impact Statement: Stationing of Mechanized or Armored Combat Forces at Fort Lewis, Washington. Fort Lewis, Washington, US Department of the ArmyGoogle Scholar
  64. Watts SE (1998) Short-term influence of tank tracks on vegetation and microphytic crusts in shrubsteppe habitat. Environmental Management 22: 611-616Google Scholar
  65. Youngman BJ (1951) Germination of old seeds. Kew Bulletin 23: 423-426Google Scholar

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Ingrid M. Parker
    • 1
  1. 1.Department of BotanyUniversity of WashingtonSeattleUSA
  2. 2.Department of Ecology and Evolutionary BiologyUniversity of CaliforniaSanta CruzUSA (e-mail

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